A non-contact charging method of the following is developed (see patent literature 1). In this non-contact charging method, a battery-equipped device equipped with a power reception coil is set on a charging stand equipped with a power transmission coil, and power is transmitted from the power transmission coil to the power reception coil, and an incorporated battery of the battery-equipped device is charged.
In this non-contact charging method, when the battery-equipped device is set on the charging stand such that the power reception coil of the battery-equipped device is electromagnetically coupled to the power transmission coil, and power is transmitted from the power transmission coil to the power reception coil, the battery is charged by power induced to the power reception coil. This charging method does not need to connect the battery-equipped device to a charger through a connector, then by non-contact charging way the incorporated battery is conveniently charged.
In this charging method, when a foreign object of a metal piece of clip or the like is set in a state of charging the battery-equipped device, induced current flowing through the foreign object generates heat of Joule heat as harmful effects. Further power is consumed by induced current flowing through the foreign object, so the battery is not efficiently charged as a demerit. In order to solve such a demerit, in the charging stand of patent literature 1, plural temperature sensors are disposed longitudinally and laterally in the upper surface. The temperature sensors detect generating heat of the foreign object set on the charging stand. In this charging stand in a state of the metal foreign object being set on it, when alternating current power is supplied to the power transmission coil, as induced current flowing through the foreign object generates heat, this charging stand detects this heat generation of the foreign object by the adjacent temperature sensor.